Multi-node computer networks may be partitioned into domains, with each domain functioning as an independent machine with its own address space. An operating system runs separately in each domain. Domain partitioning permits the resources of a computer network to be efficiently allocated to different tasks, to provide flexibility in the use of a computer system, and to provide isolation between computer resources to limit the effects of hardware or software faults in one domain from interfering with the operation of other domains of the system.
In one hardware implementation of a multi-node computer network, a grouping of central processor unit (CPU) and input/output (I/O) nodes resides in a module that is sometimes called a chassis or a cabinet. Two or more chassis may be coupled together to form a multi-node cluster. When a multiple-chassis system is partitioned into several domains, a node residing in one domain is not allowed to make read and write requests to a node in another domain. As a result, cables that couple chassis in different domains (inter-domain cables) are not used for message traffic, while the cables connecting chassis in the same domain (intra-domain cables) are heavily congested with message traffic. In a partitioned system, the intra-domain message traffic is typically greater than the inter-domain message traffic.
Previous solutions for message traffic balancing are known. HP9000 “Superdome” Server of Hewlett Packard Company of Palo Alto, Calif. is among them. This system, however, does not provide support for load balancing over unused paths in a partitioned system. Another solution used for message traffic balancing is dynamic adaptive routing, which requires a complex implementation that increases hardware cost.
Therefore, there is a need for an improved mechanism to relieve message traffic congestion in a multi-node partitioned computer system.